Valve actuation system for steam engine

ABSTRACT

A steam engine having steam inlet and exhaust poppet valves which are hydraulically actuated by water under pressure. Enginedriven rotary distributors couple a boiler feedwater pump or other source of high-pressure water to the valves, and the distributors deliver gated water pulses to actuate the valves in timed sequence. The inlet-valve distributor is adjustable to provide a variable-admission adjustable-cutoff inlet system for steam supplied to the engine cylinders.

United States Patent [151 3,662,553 Hodgkinson 1 May 16, 1972 54] VALVEACTUATION SYSTEM FOR 3,402,737 9/1968 Goldstein ..91/4s| x STEAM ENGINEZEAEJT 5754M F550 Will? SI/MP ca/voavsig Primary Examiner-Edgar W.Geoghegan Assistant E.xaminerAllen M. Ostrager Attorney-Christie, Parker& Hale ABSTRACT A steam engine having steam inlet and exhaust poppetvalves which are hydraulically actuated by water under pressure. Engine-driven rotary distributors couple a boiler feedwater pump or othersource of high-pressure water to the valves, and the distributorsdeliver gated water pulses to actuate the valves in timed sequence. Theinlet-valve distributor is adjustable to provide a variable-admissionadjustable-cutoff inlet system for steam supplied to the enginecylinders.

16 Claims, 13 Drawing Figures mmmm 16 m2 sum 0F 5 I 634 a I BACKGROUNDOF THE INVENTION A fundamental problem in designing vapor engines suchas a steam engine is the valve system which admits and exhausts steam inan expander such as a piston-cylinder chamber. The valves should becapable of quiet high-speed operation, and must operate dependably athigh temperatures associated with superheated steam. A valve system witha variable actuating cycle is normally needed to provide control overengine speed and power, plus the capability of reversing the engine.

Slide valves are well known in the steam field, but are limited in speedand unsuited for high-temperature operation. Rotary valves have alsobeen used for direct admission of steam to an expander, but these valvespresent many problems in port design and are not satisfactory withhigh-pressure, high-temperature steam. Poppet valves provide perhaps thebest sealing action of any system, but are normally actuated by acamshaft-pushrod arrangement which presents control problems and iscomplex and noisy. It is also difficult to seal the stems ofconventionally driven poppet valves to keep steam out of an oil bath inthe engine crankcase.

The valve system of this invention uses poppet valves which arehydraulically actuated by high-pressure water. The flow of water iscontrolled by a distributor such as a rotary valve which provides enginespeed and power control. Steam-sealing problems are eliminated as thevalves are isolated from the crankcase oil, and any steam or waterleakage past the valve body is harmless as steam is the working fluidused in the engine. The high-temperature capabilities and good sealingcharacteristics of poppet valves are thus utilized, while the disadvantages of prior-art actuating systems are avoided. Water underpressure to actuate the valves is conveniently obtained from a feedwaterpump used with the engine boiler.

SUMMARY OF THE INVENTION Briefly stated, this invention relates to animproved valveactuating system for a vapor engine such as a steam enginehaving an expander with a vapor valve adapted for hydraulic or fluidoperation. The engine includes a vapor generator or boiler forvaporizing a liquid-phase working fluid to drive the engine.

The valve-actuating system includes first means such as a boilerfeedwater pump and connecting lines for supplying liquid-phase workingfluid under pressure. A distributor means such as an engine-drivenrotary valve is connected between the first means and valve. Thedistributor is operated synchronously with the engine to deliver thepressurized liquid-phase working fluid to open and close the valve intimed relation to the motion of the expander.

Preferably, the system is arranged to actuate all inlet and exhaustvapor valves of the engine which are desirably poppettype valves. In oneform, the system includes a shuttle valve for minimizing fluid drainfrom water-pulse lines between the distributor means and vapor valves.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic diagram of asteam engine with a valve-drive system according to the invention;

FIG. 2 is a stepped sectional elevation of a two-cylinder reciprocatingsteam engine;

FIG. 3 is a sectional elevation of an exhaust-valve distributorassembly;

FIG. 4 is a view on line 4-4 ofFIG. 3;

FIG. 5 is a view on line 5-5 ofFIG. 3;

FIG. 6 is a view showing a surface development of a ported sleeve usedin the exhaust distributor assembly;

FIG. 7 is a sectional view of an inlet-valve distributor assem bly;

FIG. 8 is a view on line 8-8 of FIG. 7;

FIG. 9 is an elevation of a ported sleeve used in the inlet distributorassembly;

FIG. 10 is a view on line 10-10 of FIG. 9;

FIG. 11 is a sectional elevation of a shuttle-valve assembly used withthe inlet and exhaust distributors;

FIG. 12 is a view on line 12-12 ofFIG. I1; and

FIG. 13 is a sectional elevation of a portion of the engine showing aninlet poppet valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT The valve-actuation system ofthis invention will be described in terms of its use in a compounddouble-acting steam engine 10 shown schematically in FIG. 1. Engine 10has a high-pressure cylinder 11 and a low-pressure cylinder 12, butvapor engines with any number of cylinders or other types of expanderscan use the invention. Pistons 13 and 14 are fitted in the respectivecylinders, and are coupled to a crankshaft 15 by connecting rods 16. Thehigh-pressure cylinder has a pair of inlet valves 17 on opposite sidesof piston 13, and a pair of exhaust valves 18 also positioned onopposite sides of the piston. Similarly, low-pressure cylinder 12 has apair of inlet valves 19 and a pair of exhaust valves 20 respectivelypositioned on opposite sides of piston 14.

A boiler 24 is fed by a feedwater pump 25 which draws water from afeedwater sump 26. A super-heated steam line 27 is connected between theboiler and inlet valves 17 of the high-pressure cylinder. Exhaust steamfrom the high-pressure cylinder is directed back to the boiler by areheat-steam return line 28 connected to the outlet of exhaust valves18. Reheated steam from the boiler is delivered to inlet valves 19 ofthe lowpressure cylinder through a line 29. Exhaust from the lowpressurecylinder is directed through an exhaust line 30 to a condenser 31, andoutlet water from the condenser is returned to feedwater sump 26 througha water line 32.

The engine also includes an inlet-valve actuating distributor 36 and anexhaust-valve actuating distributor 37 for operating the inlet andexhaust valves of the several cylinders. The two distributors areoperated off of crankshafi 15 as suggested by dashed lines 38.High-pressure water from feedwater pump 25 is fed through a line 39 tothe distributors. Timed pulses of high-pressure water are gated into theinlet and exhaust valves through lines 40 and 41 respectively to openand close the valves hydraulically in timed sequence. A valve-drivewater return line 42 delivers water from the outlet of the valve-drivedistributors to feedwater sump 26. The valve system of the engine isdescribed in greater detail below.

The expander and valve portions of engine 10 are shown in greater detailin FIG. 2 which is a stepped sectional elevation showing low-pressurecylinder 12 and piston 14 on the left of a center line, andhigh-pressure cylinder 11 and piston 13 on the right. That is, the leftand right portions of FIG. 2 are spaced apart along an axis of rotationof crankshaft 15. The pistons are coupled by a pair of piston rods 44 toa pair of conventional crossheads 45 which are in turn connected to thecrankshaft by connecting rods 16. The crossheads reciprocatenon-compressively in bores 46 in a crankcase 47 which houses the lowerportion of the engine. Piston rods 44 pass through seals 48 mounted inan intermediate head 49 secured to the upper end of the crankcase.Cylinders 11 and 12 are defined by a cylinder block 50 secured to theupper surface of intermediate head 49 and are closed by an upper head 51fastened to the top of the cylinder block.

Poppet-type inlet and exhaust valves 19 and 20 for the lowpressurecylinder are shown at the left side of FIG. 2. The valves are generallycylindrical, and seal against valve seats 55 and 71 secured in the upperand intermediate heads. The valves are urged toward a closed position byvalve springs 56.

Inlet valve 19 is slidably mounted in a cylindrical bore 57 defined bycylinder block 50 and a hollow cap 58 fastened to the top of the upperhead. A steam inlet manifold 59 extends into communication with anannular space 60 formed just above valve seat 55 in the upper head. Asecond chamber 61 is defined eneath valve seat 55 and extends intocommunication with low-pressure cylinder 12 above piston 14. When theinlet valve is open, steam thus flows from the inlet manifold throughthe open valve into chamber 61 and the low-pressure cylinder to drivethe piston downwardly.

A step piston 65 of reduced diameter extends from the lower end of inletvalve I9 and makes a slip fit in a bore 66 in cylinder block 50. Achamber 67 at the bottom of bore 66 below the step piston is in fluidcommunication with line 40 which carries high-pressure water frominlet-valve distributor 36 secured to the side of the cylinder block.

Exhaust valve 20 of the low-pressure cylinder is mounted below the inletvalve just described, and is arranged in generally the same fashion asthe inlet valve. The exhaust valve makes a slip fit in a cylindricalbore 70 defined by intermediate head 49 and cylinder block 50, and isurged toward a closed position against a seat 71 by a spring 72. Achamber 73 extends from the lower end of the low-pressure cylinder tothe upper surface of valve seat 71, and an annular space 74 beneath thevalve seat is in communication with an exhaust manifold 75 secured tothe side of the intermediate head.

The exhaust manifold feeds into line 30 (not shown) which directsexhaust steam to the condenser (FIG. 1). A step piston 76 extends fromthe underside of exhaust valve 20 and is slidably mounted in a bore 77in the intermediate head. The undersurface of the step piston is influid communication with line 41 connected to exhaust-valve distributor37 mounted on the right side of the engine cylinder block.

Another pair of inlet and exhaust valves (not shown) are mounted on thelow-pressure cylinder. That is, a pair of inlet and exhaust valves arepositioned on each side of the low-pressure piston. A similar valvingand manifolding arrangement is provided for the high-pressure cylinderas suggested at the right side of FIG. 2. All of the inlet valves (forboth the highand low-pressure cylinders) are operated by a singleinletvalve distributor 36, and all of the exhaust valves are operated bya single exhaust-valve distributor 37, the distributors being mounted onbosses 78 on opposite sides of crankcase 47.

Exhaust-valve distributor 37 is shown in detail in FIGS. 3-6. Theexhaust distributor includes a generally cylindrical body 80 havingmounting flanges 81 (shown in FIG. 2 but omitted in FIGS. 3-6) forattachment to bosses 78. The interior of body 80 is hollow, and definesa cylindrical bore 82 closed at one end by a cover plate 83 secured tothe body. Four axially spaced and axially elongated ports or openings84ABCD extend through the upper wall of body 80, and tubularshuttlevalve housings 86 extend upwardly from body 80 over each opening.As shown in FIG. 2, lines 41 are connected to the upper end of housings86 to place the engine exhaust valves in fluid communication withopenings 84.

A tubular sleeve 90 makes a rotatable slip fit in bore 82 of theexhaust-distributor body. One end of sleeve 90 has an outwardlyextending flange 91 to which is secured a cover plate 92 having a driveshaft 93 extending therefrom. A gear 94 is rigidly secured to shaft 93and mates with another gear (not shown) driven off the engine crankshaftwhereby sleeve 90 is rotated at engine speed. A cover bell 95 isfastened to body 80 over plate 92 and shaft 93.

A plurality of spaced inlet ports IOABCD and outlet drain ports IOIABCDextend through sleeve 90 as best seen in the developed surface of thesleeve shown in FIG. 6. Each port is elongated along the circumferenceof the sleeve, and is enlarged at one end to present a low-impedancefluid path at the instant of valve opening or valve closing. A pair ofshallow webs I02 extend across each of the ports to strengthen thesleeve. The webs are recessed beneath the inner and outer surfaces ofsleeve 90 (see FIGS. 4-5) to place the several portions of each port influid communication with each other.

Ports 100A and 101A are axially positioned to pass beneath opening 84Awhich communicates through line 41 to the upper exhaust valve of thehigh-pressure cylinder. Ports [00B and IOIB are positioned to passbeneath opening 848 which communicates through line 41 to the lowerexhaust valve of the high-pressure cylinder. Similarly, ports 100C andI01C are in intermittent fluid communication through opening 84C to thelower exhaust valve of the low-pressure cylinder, and

ports D and 101D are in intermittent fluid communication through openingMD with the upper exhaust valve of the lowpressure cylinder. The portsare axially and circumferentially spaced on the sleeve to provide properphasing of the exhaust valves.

A cylindrical center manifold I05 makes a slip fit within sleeve 90 andis rigidly secured to cover plate 83 by bolts 106. An inlet chamber 107is defined by a bore which extends from one end of the center manifoldto terminate just short of the end of the manifold which is secured tocover plate 83. A drain chamber 108 is formed by a second blind borewhich similarly extends from one end of the center manifold to terminateslightly short of the blind end of inlet chamber 107. The open end ofinlet chamber I07 is sealed with a plug 109.

As best seen in FIG. 3, tubular sleeve 90 terminates short of coverplate 83, and center manifold is enlarged in diameter between the end ofthe sleeve and cover plate 83 to fit against the inner surface of body80. An annular groove 112 is formed in this enlarged-diameter portion,and is sealed on each side by O-rings 113. A slot 114 is formed betweena portion of groove I12 and inlet chamber I07 to place the entire groovein fluid communication with the inlet chamber.

An opening 115 extends through body 80 in alignment with groove I12, anda fitting 116 (FIGS. 4-5) is secured to the body over the opening. Line39 (see FIG. I) is connected to fitting 116 to deliver high-pressurewater from the feedwater pump to inlet chamber 107. An opening I17 (FIG.3) is similarly formed through housing 80, and a drain fitting I18(FIGS. 4-5) is secured over this opening for connection to water-retumline 42 (FIG. 1).

Opening 117 is aligned with a second annular groove 120 in the centermanifold, and groove 120 is cut to a sufficient depth to be in fluidcommunication with drain chamber 108. The entire drain chamber plus aspace 121 within tubular sleeve 90 between cover plate 92 and the end ofthe center manifold are thus in fluid communication with water-retumline 42. A third annular groove 122 is spaced between the ends of thecenter manifold, and is cut to a depth sufficient to extend into thedrain chamber.

As sleeve 90 is rotated at engine speed, drain ports IOIABCD cyclicallyform passages between the return chamber and openings MABCD in theexhaust-distributor body. For example, for the rotational position ofsleeve 90 shown in FIG. 3, port 101C has opened a fluid path betweenopening 84C and third annular groove 122. When port I01A rotates intoposition below opening 84A, a path is established to the return chamberthrough space 121. Similarly, port 1013 will rotate into position toform a path between opening 848 and third annular groove 122. Finally,port 1010 will rotate under opening 84D to form a fluid path to thedrain chamber through second annular groove 120. Opening of these pathsreleases water from lines 41 and the associated valves are driven closedby the valve springs.

Referring to FIGS. 3 and 5, four radially extending slots 124ABCD arecut from the surface of center manifold I05 into inlet chamber 107. Theslots are axially spaced along the manifold to be in alignment withopenings MABCD, respectively. As sleeve 90 rotates at engine speed,inlet ports IO0ABCD sequentially place the inlet chamber in fluidcommunication with openings 84ABCD whereby high-pressure water pulsesare cyclically delivered to actuate the engine exhaust valves.

For example, when sleeve 90 is in the position shown in FIG. 3, opening840 is connected to the inlet chamber through inlet port 100D. In therelative position shown in FIG. 5, a slight additional clockwiserotation of sleeve 90 will open a path through port 100A between opening84A and slot 124A in the stationary center manifold.

The exhaust-valve distributor provides constant-dwell timing as it isdesirable to hold the exhaust valves open during almost the entirereturn stroke of the piston regardless of engine speed or output power.The stationary center manifold of the exhaust-valve distributor providesthis relationship, and difi'ers from the variable-admission cycleprovided by the inlet-valve distributor to be described below.

If reversal of the steam engine is desired, re-phasing of theexhaust-valve action is readily achieved by making the center manifoldaxially movable within the distributor body. In this arrangement, asecond set of openings (not shown) are formed through the wall of themanifold to move into alignment with the tubular-sleeve ports to providethe desired reverse phasing of the exhaust valves.

Inlet-valve distributor 36 is shown in detail in FIGS. 7-10, and issimilar in many respects to the exhaust-valve distributor. Avariable-admission cycle is desired for the inlet valves, however, toprovide a speed and power control for the engine. A somewhat differentport arrangement and a movable center manifold are accordingly providedin the inlet-valve system.

Distributor 36 includes a generally cylindrical body 130 having an innerbore 131 closed at one end by a cover plate 132. Four axially spaced andelongated ports or openings 133ABCD extend through the upper surface ofthe distributor body, and tubular shuttle-valve housings 134(corresponding to housings 86) extend upwardly from the body overopenings 133. Lines 40 FIGS. 1-2) connect housings 134 to the inletvalves of the engine.

A tubular sleeve 137 makes a rotatable fit in bore 131 of theinlet-distributor body, and is secured at one end to a cover plate 138having a drive shaft 139 extending therefrom. A drive gear 140 issecured to shaft I39 and meshes with a gear (not shown) coupled to thecrankshaft whereby the sleeve is driven at engine speed. A cover bell141 is secured to the end of body 130 opposite plate 132, and extendsover drive shaft 139. Orings or other appropriate seals are providedthroughout the assembly to prevent fluid leakage.

Four circumferentially extending and axially spaced ports I44ABCID areformed through sleeve 137, and the sleeve is stiffened by recessed webs14$ extending across the ports. As seen in FIGS. 8-10, ports 144A and Bare 180' out of phase with each other, and ports 144C and D are also l80out of phase. Ports 1448 and C are 90 out of phase, resulting in a 90spacing in the four ports. This phasing provides the correct timing forthe pairs of inlet valves on each of the two engine cylinders.

A center manifold 148 makes a rotatable slip fit within tubular sleeveI37, and has a shaft 149 extending from one end through cover plate 132.The shaft is rigidly connected to a control lever 150 which provides ameans of varying the dwell of the valves by rotating manifold 148 tovary the timing of the inlet-valve operation.

A blind bore terminating slightly short of the control-lever end of thecenter manifold defines an inlet chamber 152 which is closed by a plug153. A similar bore, terminating slightly short of the end of chamber152, defines a drain chamber 154 in the center manifold.

Sleeve 137 terminates short of cover plate 132, and the end of thecenter manifold between the cover plate and sleeve is enlarged indiameter to bear against the inner surface of body 130. An annulargroove 155 in the enlarged end of center manifold 148 is cut to a depthsufficient to extend into inlet chamber 152, and places the inletchamber in fluid communication with an opening 157 through body 130. Afitting 158 (FIG. 8) is secured over opening 157, and is adapted forconnection to high-pressure water line 39 (FIG. 1) from the feedwaterpump. Water under pressure is thus delivered to the inlet chamber of thecenter manifold regardless of the rotational position of the manifoldwithin body 130.

A second annular groove 160 is formed in the periphery of the centermanifold between sleeve 137 and the enlarged end of the manifold. A slot161 extends inwardly from a portion of groove 160 to place the grooveand drain chamber 154 in fluid communication with an opening 162 in body130. A fitting 163 (FIG. 8) is secured to the body over opening 162 forconnection to water-retum line 42 (FIG. 1).

Four elongated. axially aligned ports or slots 164ABCD extend throughthe wall of the center manifold into inlet chamber 152. The slots arepositioned to match the axial spacing of openings 133ABCD respectively.A similar set of slots 165ABCD are formed through the wall of the centermanifold into drain chamber 154, and slots 164 and 165 are spaced 180apart. As best seen in FIG. 8, ports 144 extend slightly less than 180around the periphery of sleeve I37, whereby the slots 164 and 165associated with any particular opening 133 are never openedsimultaneously.

Rotation of center manifold 148 by control lever 150 varies the durationof steam admission to each cylinder by varying the operating cycle (thenumber of degrees of crankshaft rotation during which an inlet valve isheld open) of the associated inlet valves. The particular manifoldposition selected determines the duration of steam admission (which canbe set at any point from 0 to almost 180 of crankshaft rotation) andhence the engine speed and power.

The manifold is shown in FIG. 8 in a fully cutoff position where nohigh-pressure water is delivered to the inlet valves, and thus no steamis admitted to the engine cylinders. Rotation of the manifold away fromthe cutoff position produces actuation of the inlet valves, withvalve-closure timing being related to the rotational position of themanifold.

A shuttle-valve assembly (FIGS. 11-12) is preferably used in each of thelines connecting the inletand outlet-valve actuating distributors to therespective valves. The assemblies are installed in shuttle-valvehousings 86 and 134 on the respective distributors, and are used tominimize the amount of water drained from the valves and lines 40 and 41when the valves are closed. This feature improves the efiiciency andoperating speed of the valve-actuating system as the volume of waterpumped during valve actuation is minimized by the shuttle valve.

Referring to FIGS. 11-12, the interior of the shuttle-valve housingdefines a smooth cylindrical bore 171, and a cylindrical guide sleeve172 is fitted in the bore to abut an inwardly extending annular shoulder173 at the bottom of bore 171. An upper portion of sleeve 172 is reducedin diameter to define an upwardly extending annular flange 174. Theguide sleeve is locked in position by a retainer 175 which is threadedinto the upper end of the shuttle-valve housing.

Retainer 175 has a downwardly extending annular flange 178 which makes aslip fit within bore 171 and bears against an annular shoulder 179 ofthe guide sleeve. A hollow fitting 180 is threaded into the top ofretainer 175, and fluid line 40 or 41 to the inlet or exhaust valve isconnected to this fitting.

An outer annular chamber 182 is defined by the space between the innersurface of flange 178 and the outer surface of flange 174, and an innercylindrical chamber 183 is defined by the inside surface of flange 174.A cup-shaped shuttle valve 184 makes a slip fit in chamber 183, and thebottom of the shuttle valve is inwardly tapered to mate with a seat 185formed toward the lower end of chamber 183.

A plurality of downwardly extending notches 186 are formed in the upperedge of the shuttle valve, and a plurality of ports 187 extend throughflange 174 of the guide sleeve above the seated shuttle valve. The spacebelow the seated shuttle valve is in direct fluid communication withopening 84 or 133 in the body of the exhaust or inlet distributorrespectively.

When the distributor rotates into a position to deliver highpressurewater through opening 84 or 133, the shuttle valve is driven upwardly inchamber 183. If no water is present in the chamber above the shuttlevalve, the valve will more upwardly until it abuts the under-surface ofretainer 175 as shown in phantom in FIG. 11. Any additional water neededto actuate the valve flows through ports 187, then upwardly in outerannular chamber 182 through notches 186 into fitting 180.

When the supply of high-pressure water to the engine valve is cut off bythe distributor, the column of water between the distributor and enginevalve is moved back toward the distn'butor by the closure springassociated with the engine valve. This motion of the water column drivesshuttle valve 184 downwardly into a seated position as shown in solidline in FIG. 11. Once the valve is seated, no further water is drainedinto the distributor, and a column of water is trapped in the linecoupling the the distributor and engine valve. When the engine valve issubsequently actuated, the shuttle valve moves upwardly in chamber I83only a sufficient distance to displace the trapped column of waterenough to fully open the engine valve.

A slightly modified version of an engine-valve assembly 190 useful inengine 10 is shown in FIG. 13. Assembly 190 includes a generallycylindrical poppet valve 191 having an upper end making a slip fit in acylindrical bore I92 in upper head 51. An annular valve seat 193 isrigidly secured in the top of cylinder block 50, and the inner surfaceof the seat defines a bore 194 in which the lower part of poppet valve191 makes a reciprocating slip fit. The poppet valve and seat havemating surfaces 195 which seat against each other when the valve isclosed.

A step-piston 197 of reduced diameter extends from the bottom of poppetvalve 191, and makes a slip fit in a bore 198 in the cylinder head. Apassage [99 in the bottom of bore 198 below the step piston extends intocommunication with line 40 (not shown) which connects the assembly tothe inlet-valve distributor. A cap 200 is threaded into the upper headabove valve I91, and a valve-closure spring 201 is positioned in thehollow interior of the poppet valve. The spring is compressed by cap200, and urges the poppet valve into a closed position.

A steam inlet manifold 203 receives steam from the boiler (not shown),and the manifold is secured to the side of the upper head and cylinderblock of the engine. An inlet nozzle 204 is formed in the inlet manifoldand upper head, and extends into communication with an annular chamber205 in the upper head above valve seat 193 and mating surfaces 195.Poppet valve 191 is reduced in diameter below mating surfaces l95 todefine an annular chamber 206. Another chamber 207 is defined betweenupper head 51 and the top of cylinder block 50, and chamber 207 extendsaround the periphery of seat 193 and into communication with the enginecylinder. A plurality of radially extending ports 208 are drilledthrough the wall of valve seat 193 to open a steam passage betweenchambers 206 and 207. Appropriate seals 209 are provided throughout thevalve assembly.

Poppet valve 191 is normally held in a closed position as shown in FIG.l3 by spring 20], and by the high-pressure steam in chamber 205 whichforces the valve downwardly against seat 193. When the valve is to beopened, a high-pressure pulse of water is gated into passage [99 fromthe associated valve-actuating distributor. The water acts against theundersurface of the step piston to raise the poppet valve, and matingsurfaces 195 are separated to admit steam into chamber 206. The steamthen passes through ports 208 into chamber 207 to flow into theassociated cylinder (not shown in FIG. 13). The valve is essentiallybalanced when it is open, but closes immediately when the associateddistributor rotates into a position to release the water pressure inpassage 199.

Several outlet ports 212 extend through the undersurface of poppet valve19! around the periphery of step piston 197. Any steam which leaks pastthe upper seals of the poppet valve passes into the interior of thevalve body and then through outlet ports 212 into a passage 213 belowseat 193. Steam in this passage is returned to condenser 31.

The reduced-diameter step piston at the bottom of poppet valve 19! isused to minimize the amount of high-pressure water which must bedelivered from the distributor to open the valve. The step piston can beeliminated if high-speed valve actuation is not required, and bothstyles of valves are shown in the sectional view of FIG. 2. Valveassembly 190 can also be used as an exhaust valve, but in this case theporting of the valve system is rearranged so the upper part of the valveis in communication with the engine cylinder. That is, the exhaust valveis arranged so it is urged into a seated position by high-pressure steamin the associated engine cylinder.

A significant feature of the valve-actuating system of this invention isthat the hydraulic fluid used to operate the engine valves is the sameworking fluid which (in a vapor phase) operates the engine. As a result,any leakage which mixes the hydraulic and working fluids is harmless,and the severe sealing problems encountered in conventional systems canbe ignored. Any valve-actuating water which leaks through the systeminto the engine cylinders will vaporize harmlessly to steam and beexhausted back to the boiler system. There is thus no concern overcontamination of the engine working fluid with the valve-actuatinghydraulic fluid since the two fluids are vapor and liquid phases of thesame material (water of any other fluid which is selected to drive theengine). The system is also advantageous in that separate pumps are notrequired as the same feedwater pump which supplies the engine boiler canalso supply high-pressure water to the valveactuation distributors.

The mechanical rotary-valve distributor means described above is apresently preferred embodiment of the invention as it provides reliablehigh-speed gating of water pulses to actuate the valves. Otherapproaches to the gating function are believed feasible, and areintended to fall within the scope of the invention. For example,high-speed solenoid-actuated electric valves can be connected betweenthe engine steam valves and the source of high pressure water. Anengine-driven electric switch is used to open and close the solenoidvalves to actuate the engine valves in timed relation to crankshaftrotation. The switch is adapted to vary the dwell or open cycle of theengine valves for speed and power control, and valve-actuation permitreverse operation.

There has been described a valve-actuation system providingvariable-admission control for a vapor engine. The system is capable ofhigh-speed valve actuation, and is free from oilcontamination and othersevere sealing problems which characterize known steam engines.

What is claimed is:

1. [n a vapor engine having an expander with a vaporadmitting inletvalve adapted for fluid actuation, and a vapor generator for vaporizinga liquid-phase working fluid to drive the engine, a variable admissionvalve-actuating system comprising:

first means for supplying the liquid-phase working fluid under pressure;and

distributor means connected to the first means and the inlet valve, andcoupled to the expander to operate synchronously therewith to deliveractuating pulses of the pressurized liquid-phase working fluid to theinlet valve to operate the valve in adjustable timed relation to motionof the expander.

2. The improvement defined in claim I in which the expander is areciprocating piston-cylinder type, and the inlet valve is a poppetvalve.

3. The improvement defined in claim 2 in which the distributor means isa rotary valve driven by the engine and connected by a fluid-carryingline to the inlet valve.

4. The improvement defined in claim 3 in which the rotary valve isadjustable to operate the inlet valve for forward and reverse operationof the engine, the liquid-phase working fluid is water, and the firstmeans is a feedwater pump supplying water to the vapor generator and tothe rotary valve.

5. The improvement defined in claim 4 and further comprising means inthe line connecting the rotary and inlet valves for limiting reverseflow of water from the inlet valve toward the rotary valve when theinlet valve is closed, whereby a quantity of water is trapped in theline during engine operation.

6. In a reciprocating steam engine having a piston-cylinder expander, awater reservoir, and a boiler for heating water to produce steam todrive the expander, a valving system comprising:

inlet and exhaust valves on the expander and adapted for hydraulicoperation by a pressurized fluid;

a pump connected to the reservoir to deliver water under pressure; and

distributor means driven by the expander and connected between the pumpand valves to admit water under pressure to the valves to actuate thevalves in a predetermined adjustable sequence.

7. The improvement of claim 6 in which the inlet and exhaust valves arepoppet-type valves mounted in the engine to control steam flow into andout of the expander, each valve having a closure spring urging the valveinto a seated, closed position, the valves being movably mounted inbores in the engine, each bore defining a chamber at one end of theassociated valve, the chamber being in fluid communication with thedistributor means to receive water under pressure which moves the valveagainst the closure spring into an open position.

8. The improvement of claim 7 in which said one end of at least one ofthe poppet valves is reduced in diameter to define a step piston againstwhich water under pressure from the distributor means acts to open thevalve.

9. The improvement of claim 6 in which the distributor means and valvesare connected by separate water lines, at least one of the linesincluding a shuttle valve for limiting reverse flow of water from thevalve toward the distributor means.

10. The improvement of claim 9 in which the shuttle valve is ported topermit free forward water flow from the distributor means to the valve.

11. The improvement of claim 6 in which the pump is a feedwater pumpconnected to the reservoir to deliver water under pressure to both thedistributor means and the boiler.

12. The improvement of claim 6 in which the distributor means includes arotary valve with a variable operating cycle to gate adjustable-durationwater pulses to the inlet valve.

13. The improvement of claim 6 in which the distributor means comprisesa first rotary valve to drive the inlet valve, and a second rotary valveto drive the exhaust valve.

14. The improvement of claim 13 in which the engine has at least twoinlet and two exhaust valves, and in which each rotary valve comprises ahollow housing secured to the engine and having ports in fluidconnection with the associated valves, a sleeve rotatably mounted in thehousing and connected to the engine to be rotated thereby in synchronismwith engine-piston motion, the sleeve having ports alignable withselected housing ports during a portion of each rotation of the sleeve,and a center manifold making a slip fit within the sleeve and having adrain chamber, and an inlet chamber in fluid communication with thepump, each chamber having ports opening into the sleeve ports during aportion of each sleeve rotation whereby gated water pulses are deliveredto and released from the valves.

15. The improvement of claim 14 in which the center manifold of thefirst rotary valve is movably mounted to be adjustable in rotationalposition with respect to the housing whereby the duration of steamadmission to the expander through the inlet valves is adjustable.

16. The improvement of claim 15 in which the inlet and exhaust valvesare poppebtype valves mounted in the engine to control steam flow intoand out of the expander, each valve having a closure spring urging thevalve into a seated, closed position, the valves being movably mountedin bores in the engine, each bore defining a chamber at one end of theassociated valve, the chamber being in fluid communication with theassociated rotary valve through a conduit to receive water underpressure which moves the valve against the closure spring; and furthercomprising a shuttle valve in each conduit for limiting reverse flow ofwater toward the rotary valve; the pump being connected to deliver waterunder pressure to the boiler and the rotary valves.

II I t I i g ga UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,662,553 Dated ligy 16, 1972 Inventor (s) Robert HodgkinsonIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Colum 5, line 23, "Lines #0 FIGS. 1-2)" should read --Lines 40 (FIGS.l-2)--.

Column 6, line 65, "more" should read --move--.

Column 8, line 11, "of" should read or Column 8, line 28, after and",second occurrence insert to delete "valve actuation".

Signed and sealed this Zhth day of October 1972.

(SEAL) Attest:

EDWAPD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer Commissionerof Pa tents

1. In a vapor engine having an expander with a vapor-admitting inletvalve adapted for fluid actuation, and a vapor generator for vaporizinga liquid-phase working fluid to drive the engine, a variable admissionvalve-actuating system comprising: first means for supplying theliquid-phase working fluid under pressure; and distributor meansconnected to the first means and the inlet valve, and coupled to theexpander to operate synchronously therewith to deliver actuating pulsesof the pressurized liquid-phase working fluid to the inlet valve tooperate the valve in adjustable timed relation to motion of theexpander.
 2. The improvement defined in claim 1 in which the expander isa reciprocating piston-cylinder type, and the inlet valve is a poppetvalve.
 3. The improvement defined in claim 2 in which the distributormeans is a rotary valve driven by the engine and connected by afluid-carrying line to the inlet valve.
 4. The improvement defined inclaim 3 in which the rotary valve is adjustable to operate the inletvalve for forward and reverse operation of the engine, the liquid-phaseworking fluid is water, and the first means is a feedwater pumpsupplying water to the vapor generator and to the rotary valve.
 5. Theimprovement defined in claim 4 and further comprising means in the lineconnecting the rotary and inlet valves for limiting reverse flow ofwater from the inlet valve toward the rotary valve when the inlet valveis closed, whereby a quantity of water is trapped in the line duringengine operation.
 6. In a reciprocating steam engine having apiston-cylinder expander, a water reservoir, and a boiler for heatingwater to produce steam to drive the expander, a valving systemcomprising: inlet and exhaust valves on the expander and adapted forhydraulic operation by a pressurized fluid; a pump connected to thereservoir to deliver water under pressure; and distributor means drivenby the expander and connected between the pump and valves to admit waterunder pressure to the valves to actuate the valves in a predeterminedadjustable sequence.
 7. The improvement of claim 6 in which the inletand exhaust valves are poppet-type valves mounted in the engine tocontrol steam flow into and out of the expander, each valve having aclosure spring urging the valve into a seated, closed position, thevalves being movably mounted in bores in the engine, each bore defininga chamber at one end of the associated valve, the chamber being in fluidcommunication with the distributor means to receive water under pressurewhich moves the valve against the closure spring into an open position.8. The improvement of claim 7 in which said one end of at least one ofthe poppet valves is reduced in diameter to define a step piston againstwhich water under pressure from the distributor means acts to open thevalve.
 9. The improvement of claim 6 in which the distributor means andvalves are connected by separate water lines, at least one of the linesincluding a shuttle valve for limiting reverse flow of water from thevalve toward the distributor means.
 10. The improvement of claim 9 inwhich the shuttle valve is ported to permit free forward water flow fromthe distributor means to the valve.
 11. The improvement of claim 6 inwhich the pump is a feedwater pump connected to the reservoir to deliverwater under pressure to both the distributor means and the boiler. 12.The improvement of claim 6 in which the distributor means includes arotary valve with a variable operating cycle to gate adjustable-durationwater pulses to the inlet valve.
 13. The improvement of claim 6 in whIchthe distributor means comprises a first rotary valve to drive the inletvalve, and a second rotary valve to drive the exhaust valve.
 14. Theimprovement of claim 13 in which the engine has at least two inlet andtwo exhaust valves, and in which each rotary valve comprises a hollowhousing secured to the engine and having ports in fluid connection withthe associated valves, a sleeve rotatably mounted in the housing andconnected to the engine to be rotated thereby in synchronism withengine-piston motion, the sleeve having ports alignable with selectedhousing ports during a portion of each rotation of the sleeve, and acenter manifold making a slip fit within the sleeve and having a drainchamber, and an inlet chamber in fluid communication with the pump, eachchamber having ports opening into the sleeve ports during a portion ofeach sleeve rotation whereby gated water pulses are delivered to andreleased from the valves.
 15. The improvement of claim 14 in which thecenter manifold of the first rotary valve is movably mounted to beadjustable in rotational position with respect to the housing wherebythe duration of steam admission to the expander through the inlet valvesis adjustable.
 16. The improvement of claim 15 in which the inlet andexhaust valves are poppet-type valves mounted in the engine to controlsteam flow into and out of the expander, each valve having a closurespring urging the valve into a seated, closed position, the valves beingmovably mounted in bores in the engine, each bore defining a chamber atone end of the associated valve, the chamber being in fluidcommunication with the associated rotary valve through a conduit toreceive water under pressure which moves the valve against the closurespring; and further comprising a shuttle valve in each conduit forlimiting reverse flow of water toward the rotary valve; the pump beingconnected to deliver water under pressure to the boiler and the rotaryvalves.